Another name for My Little Pony.
Some of us Bronies like to address the show as Friendship is Magic instead of saying My Little Pony because people might associate that name with the previous generations of my little pony.
But if you say "hey do you watch Friendship is Magic?" they'll more likely think of the new version instead of associating it with the old girly baby versions.

Or it's just the last name for the show My Little Pony: Friendship is Magic.